1. Technical Field of the Invention
The present invention generally relates to arbitration techniques. More particularly, and not by way of any limitation, the present invention is directed to a Parallel Round-Robin Arbiter (PRRA) system and method for arbitrating among a plurality of requesters.
2. Description of Related Art
Arbitration is a widely used technique for resolving contention among a plurality of entities that generate simultaneous requests with respect to one or more common resources. For example, in a crossbar switch application where multiple data input queues need to be switched to a number of output ports, an arbitration scheme is typically employed for deciding how the input data is to be scheduled through a switching fabric disposed between the inputs and the outputs. As a basic building block of a scheduler, accordingly, design of a fast and fair arbiter is critical to the efficiency of the scheduling process, which is the key to the performance of a high-speed switching apparatus.
Known hardware-based arbiter designs involve a Round-Robin arbitration (RRA) methodology where the basic components of some of the designs comprise various circuit blocks such as encoders, multiplexers, barrel shifters, carry-look-ahead circuits, and the like. Although these designs may be adequate in some applications, they are nevertheless afflicted with certain deficiencies. For example, the conventional hardware RRA designs have a rather formidable AT complexity (the product of time and chip area), that is, the designs involve longer arbitration times while taking up an inordinate amount of circuitry.